Techniques for improving the reliability of data transmission to a communication receiver, such as a portable selective call receiver, are well known. Various error-correcting codes, e.g., the Golay and POCSAG codes, have been in use for many years. Another technique for improving the reliability of data transmission is to retransmit the same data two, three, or more times separated in time by a predetermined interval.
While the latter method generally is preferred for applications in which there are periods of reception fading longer than can be corrected solely by the error-correcting code, retransmissions also bring an accompanying problem. The problem occurs because portable communication receivers use battery-saving techniques to conserve power during periods of transmission inactivity in order to extend the battery life. Battery life is an operational feature considered extremely important by many users of portable communication receivers. A system that retransmits the same message multiple times tends to diminish the effectiveness of the battery-saving techniques (thus shortening battery life), because the retransmissions keep "waking up" the battery-saving circuitry of the receiver, thereby repeatedly placing the receiver in a higher power consumption state than would otherwise be the case.
Thus, what is needed is a way of reducing the waste of power that occurs in the conventional battery-saving receiver when operating in a multiple retransmission environment, while retaining the transmission reliability enhancements thereof.